What: /sys/bus/w1/devices/.../alarms Date: May 2020 Contact: Akira Shimahara Description: (RW) read or write TH and TL (Temperature High an Low) alarms. Values shall be space separated and in the device range (typical -55 degC to 125 degC), if not values will be trimmed to device min/max capabilities. Values are integer as they are stored in a 8bit register in the device. Lowest value is automatically put to TL. Once set, alarms could be search at master level, refer to Documentation/w1/w1-generic.rst for detailed information Users: any user space application which wants to communicate with w1_term device What: /sys/bus/w1/devices/.../eeprom_cmd Date: May 2020 Contact: Akira Shimahara Description: (WO) writing that file will either trigger a save of the device data to its embedded EEPROM, either restore data embedded in device EEPROM. Be aware that devices support limited EEPROM writing cycles (typical 50k) * 'save': save device RAM to EEPROM * 'restore': restore EEPROM data in device RAM Users: any user space application which wants to communicate with w1_term device What: /sys/bus/w1/devices/.../ext_power Date: May 2020 Contact: Akira Shimahara Description: (RO) return the power status by asking the device * '0': device parasite powered * '1': device externally powered * '-xx': xx is kernel error when reading power status Users: any user space application which wants to communicate with w1_term device What: /sys/bus/w1/devices/.../resolution Date: May 2020 Contact: Akira Shimahara Description: (RW) get or set the device resolution (on supported devices, if not, this entry is not present). Note that the resolution will be changed only in device RAM, so it will be cleared when power is lost. Trigger a 'save' to EEPROM command to keep values after power-on. Read or write are : * '9..14': device resolution in bit or resolution to set in bit * '-xx': xx is kernel error when reading the resolution * Anything else: do nothing Some DS18B20 clones are fixed in 12-bit resolution, so the actual resolution is read back from the chip and verified. Error is reported if the results differ. Users: any user space application which wants to communicate with w1_term device What: /sys/bus/w1/devices/.../temperature Date: May 2020 Contact: Akira Shimahara Description: (RO) return the temperature in 1/1000 degC. * If a bulk read has been triggered, it will directly return the temperature computed when the bulk read occurred, if available. If not yet available, nothing is returned (a debug kernel message is sent), you should retry later on. * If no bulk read has been triggered, it will trigger a conversion and send the result. Note that the conversion duration depend on the resolution (if device support this feature). It takes 94ms in 9bits resolution, 750ms for 12bits. Users: any user space application which wants to communicate with w1_term device What: /sys/bus/w1/devices/.../w1_slave Date: May 2020 Contact: Akira Shimahara Description: (RW) return the temperature in 1/1000 degC. *read*: return 2 lines with the hexa output data sent on the bus, return the CRC check and temperature in 1/1000 degC *write*: * '0' : save the 2 or 3 bytes to the device EEPROM (i.e. TH, TL and config register) * '9..14' : set the device resolution in RAM (if supported) * Anything else: do nothing refer to Documentation/w1/slaves/w1_therm.rst for detailed information. Users: any user space application which wants to communicate with w1_term device What: /sys/bus/w1/devices/w1_bus_masterXX/therm_bulk_read Date: May 2020 Contact: Akira Shimahara Description: (RW) trigger a bulk read conversion. read the status *read*: * '-1': conversion in progress on at least 1 sensor * '1' : conversion complete but at least one sensor value has not been read yet * '0' : no bulk operation. Reading temperature will trigger a conversion on each device *write*: 'trigger': trigger a bulk read on all supporting devices on the bus Note that if a bulk read is sent but one sensor is not read immediately, the next access to temperature on this device will return the temperature measured at the time of issue of the bulk read command (not the current temperature). Users: any user space application which wants to communicate with w1_term device What: /sys/bus/w1/devices/.../conv_time Date: July 2020 Contact: Ivan Zaentsev Description: (RW) Get, set, or measure a temperature conversion time. The setting remains active until a resolution change. Then it is reset to default (datasheet) conversion time for a new resolution. *read*: Actual conversion time in milliseconds. *write*: * '0': Set the default conversion time from the datasheet. * '1': Measure and set the conversion time. Make a single temperature conversion, measure an actual value. Increase it by 20% for temperature range. A new conversion time can be obtained by reading this same attribute. * other positive value: Set the conversion time in milliseconds. Users: An application using the w1_term device What: /sys/bus/w1/devices/.../features Date: July 2020 Contact: Ivan Zaentsev Description: (RW) Control optional driver settings. Bit masks to read/write (bitwise OR): == ============================================================ 1 Enable check for conversion success. If byte 6 of scratchpad memory is 0xC after conversion, and temperature reads 85.00 (powerup value) or 127.94 (insufficient power) - return a conversion error. 2 Enable poll for conversion completion. Generate read cycles after the conversion start and wait for 1's. In parasite power mode this feature is not available. == ============================================================ *read*: Currently selected features. *write*: Select features. Users: An application using the w1_term device